Conveyor belts are known. In more detail, it transpires that some of these must also provide lateral containment sides, with the obvious aim of preventing the material being transported from spilling over from the belt itself during movement. Therefore, it is understandable that the problem is more widely experienced in these belt types, structured for carrying loose products.
The need to provide sides should, however, be reconciled with the needs of the working installations provided, which, not only due to the nature of the environment where they must be placed, but also due to proper intrinsic needs, can require sinuous paths, as well as for stretches where the ring closed conveyor belt, is then forced to rotate around a terminal guide or dragging wheel, to invert the direction of advancement.
In some cases, it is simply a case of increasing the lateral ends of the belt, very often, for instance, joining a continuous profile with rounded thickness astride and along the edge, which does not create problems either in the case of indirect paths, adapting itself perfectly, or in the case of ring closed belts with to-and-fro paths of the up-down type. However, due to the quantity and type of the material to be carried, very often it is necessary to provide higher sides, in such a way as to provide a considerably deeper material containment channel with respect to conventional belts.
The increase of the channel depth, and consequently the increasing of the height of the sides creates several problems, above all recalling the drawbacks that in a first instance, with the use of low sides, seemed to have been resolved.
Prior Art
U.S. Pat. No. 3,750,864 (Nolte) is among the first significant proposals in which it was perceived that the sides could be flexible, in this case in rubber, and with a typically corrugated profile. The corrugated shape of said sides is obtained by longitudinally juxtaposing in a continuous way, and for each of the two sides of the belt, single fan-shaped open portions, so that the sides extend adapting to the bending radius imposed by the installation when the belt reverses the rotation direction in correspondence to the wheel.
The aforementioned solution has given rise to numerous variations. For example, DE4220872 (Hartmann) suggests a side with a different profile. This concerns a product in shaped plastic material with a profile that along the upper border appears substantially undulated and constant. The lower part of the product is instead obtained with a flat base portion, which allows easier anchorage along the edge of the support belt. Finally, the oblique beads that involve about three-quarters the side height development, allow the localized stiffening of said side.
State of the art most similar to the invention
The use of so-called flex or flexible sides that laterally define a certain conveyor belt type are therefore commonly used today. The problems that are therefore faced by the manufacturers of these said belt types are substantially of an economic nature, since it is evident that to produce said belts in large quantities they must determine reasonable solutions that identify a good compromise in terms of quality, production cost and times.
The same applicant company (Habasit), as is probable with other enterprises in the sector, had to design a solution to accelerate and to contain the costs of the known moulding processes. However, the first prototype immediately proved to be ineffective due to the technical-constructive characteristics and in conclusion inadequate. The invention, in more detail consists in providing a die, shaped according to a series of continuous and symmetric depressions, above which is to be placed a predetermined portion of a flat plate in plastic material, curving upstream from a coil. Once the plate has been positioned, aluminum stripping plates are placed on top, with circulating water, that act as an electrode that shapes at a high frequency the portion of positioned plate. At the end of the moulding process, the stripping plates are to be lifted, together with the plate, to thus position a new portion that is to be shaped and cycle is to be repeated.
A previous solution, in chronological order, has been described in FR1443291 (Tricot). In the latter, a working method for obtaining a container edge for conveyor belts is described. In more detail, downstream of a supply line of an elastomer band in plastic materials, an apparatus is provided for the permanent and undulated deformation of said band. The apparatus in question is made up of two coupled moulding units by which said band is transported. Each moulding unit is made up of two wheels, of which at least one is a driver, between these two wheels a chain is extended that supports a plurality of conical-shaped dies in alignment. Said two units being almost identical and paired, the first unit makes provision for the dies to rest between the others of the opposite shaping unit, in such a way as to obtain an alternating development of shapes and counter-shapes that will transfer, vulcanizing the assembly, the relative form to the band, that is dragged downstream and contextually deformed by said moulding unit.
On the base of the teaching described above the proposal mentioned in EP0802038 (Borri et al.) has been developed. Fundamentally, it also has as an object a method and an apparatus for producing a conveyor belt with undulated lateral sides. In more detail, a band made in plastic material, to form the wall of a conveyor belt is subjected to a continuous and preliminary moulding operation, which provides said plastic material band with a corrugated profile. Also in this case, as in FR1443291 (Tricot), working is made possible by means of two coupled moulding units, each including two wheels, of which one is a driver, between each of these wheels a counter-rotating chain is extended that perpendicularly supports a plurality of parallel appendices. These appendices constitute the moulding members that when heated rest perpendicularly on the plastic material band. Portions of said continuous preformed band are subsequently welded over the surface of the belt by joining means for separate welding.
Drawbacks
Briefly, it is possible to affirm that the aforementioned Habasit proposal (stage die) is, for various reasons, substantially inadequate to fulfill the needs of current industrial level manufacturing of belts with container sides. Firstly, the suggested technical solution is not consistent with the prescribed working environment safety standard criteria, thus it would be particularly dangerous, and would therefore require at least suitable screening systems that, as a whole, would raise the respective production costs exponentially. Secondly, the Habasit solution requires the presence of an operator, as it is not automated, and finally, it presents reduced production capacity. In conclusion, considering the work to be carried out, it would constitute a non-competitive apparatus that is unjustifiable at the level of production and management costs.
The proposals EP0802038 (Borri et al.) like FR1443291 (Tricot) seem ineffective. However, it is the opinion of the applicant that they also fail to offer an effective alternative to traditional working methods. Firstly, the apparatus employed is particularly cumbersome due to its linear development that is complex and difficult to adjust. Secondly, it does not seem particularly versatile, due to the fact that working is in a certain way connected to the moulding members. The eventual substitution of the latter requires a complex and laborious intervention with excessive machine down time. Finally, a further disadvantage is linked to consumption, and this is due to the fact that a convection chamber heating system is used if the flexible band is transported. This system is particularly wasteful, as the heat tends to disperse rapidly and also heats where heating is not necessary.
Here the need to identify improved solutions is more convenient.